Exam #5: Pancreas

Question 1

What are the three key cell types that are important to the exocrine function of the pancreas?

Answer 1

1) Acinar cells= protein synthesis
2) Duct cells= fluid & bicarbonate
3) Goblet cells mucin synthesis & secretion

Question 2

What are the acinar cells of the pancreas? What is the function of the acinar cells of the pancreas?

Answer 2

Acinar cells are the protein synthesizing cells that:

• Secrete digestive enzymes
• Secrete fluid

Question 3

What are duct cells & what do they produce?

Answer 3

Duct cells are cells lining the ducts of the pancreas that function in:

• Bicarbonate secretion
• Ion transport
• Fluid transport

Generally, the duct cells have a product that is PROTECTIVE

Question 4

What are goblet cells & what do they produce?

Answer 4

Goblet cells produce mucin that:

• lubricates
• hydrates
• protects
• immune function

Question 5

What are the two primary stimuli for fluid and enzyme secretion by pancreatic acinar cells?

Answer 5

• **CCK & ACh
• CCK promotes fluid & enzyme secretion (which is enhanced by VIP or secretin)

*****Note that these two signals also promote the secretion of cholride, leading to Na+ & H20 accumulation in the lumen of the pancreatic ducts

Question 6

What are the zymogens produced by the pancreas? How are zymogens stored in the pancreas?

Answer 6

Trypsinogen* 
Chymotrypsin
Proelastease 
Proprotease E 
Procarboxypeptidase A 
Procarboxypeptidase B 

*****These are inactive proteases in the pancreas

Question 7

How are zymogens activated in the duodenum?

Answer 7

• Secreted in an inactive form & travel from: 1) pancreatic duct, 2) common bile duct, 3) duodenum
• In duodenum, trypsinogen is converted to trypsin via enterokinase that is secreted by duodenal cells; trypsin activates the other proteases

Question 8

What is the primary stimulus for the secretion of bicarbonate from the pancreatic duct cells?

Answer 8

• ***Secretin action on pancreatic duct cells
  1) Low duodenal pH= secretin secretion
  2) Secretin mainly induces duct cell secretion of bicarbonate

Question 9

How does else does secretin regulate acid secretion?

Answer 9

1) Increased release of somatostatin from gastric D-cells
2) Decreased gastrin secretion from G-cells
3) Decrease proton pump expression by parietal cells

Question 10

What are the three phases of pancreatic secretion?

Answer 10

1) Cephalic
2) Gastric
3) Intestinal

Question 11

What happens in the Cephalic phase of pancreatic secretion?

Answer 11

Vagal pathways induce pancreatic enzyme secretion in response to site, taste, smell, & mastication

Question 12

What happens in the Gastric phase of pancreatic secretion?

Answer 12

Vagal/ Gastrin induce pancreatic enzyme secretion in response to distention, gastrin, and peptides in the stomach

Question 13

What happens in the Intestinal phase of pancreatic secretion?

Answer 13

CCK, Secretin, & Enterpancreatic reflexes lead to pancreatic enzymes secretion in response to amino acids, fats, and H+ in the small intestine

*****Note that this is the phase the results in the majority of maximum enzyme secretion

Question 14

What is the stimulus for returning the levels of pancreatic secretion from the fed state to the interdigestive state?

Answer 14

Once the contents of the intestines reach the ILEUM, fats in the ileum induce the release of Peptide YY & Somatostatin; these hormones return pancreatic secretions to interdigestive levels

Question 15

What are the regulators of the cyclic pattern seen in the MMC?

Answer 15

1) Stimulation of the PNS pathways
2) CCK
3) Inihibition by a a-adrenergic input

Question 16

What cell type secretes CCK? What is the key stimulus for this cell to release CCK?

Answer 16

• I-cell

- Lipids

Question 17

Aside from the zymogens, what are the other pancreatic enzymes that are secreted?

Answer 17

Active enzymes are secreted from the pancreas in addition to the inactive proteases:

• a-amylase
• Carboxyle ester lipase
• RNase
• DNase
• Colipase
• Trypsin inhibitor

Question 18

What is pancreatitis?

Answer 18

Inflammation of the pancreas

Question 19

What is acute pancreatitis?

Answer 19

Acute inflammation of the pancreas associated typically with alcoholism or obstruction of the pancreatic or common bile duct leading to:

• Autodigestion of pancreas
• Inflammatory mediators released
• Damage to other tissues
• Malabsorption of dietary nutrients

Question 20

What is chronic pacreatitis?

Answer 20

Continued damage of the pancreas, typically from alcohol abuse

Question 21

What can pancreatitis lead to?

Answer 21

• Malabsorption Syndrome

- Cancer i.e. adenocarcinoma of the pancreas

Question 22

Overview the anatomy of the pancreas i.e. how do pancreatic enzymes get into the duodenum?

Answer 22

1) Pancreatic enzymes released from acinar cells into pancreatic duct
2) Pancreatic duct–>common bile duct
3) Common bile duct–>duodenum via “Sphincter of Oddi “